Phase-locked diode lasers

VCSELs are promising diode lasers for many applications. The fabrication of VCSELs in 2D arrays is relatively easy but to increase not only the total power but also the power density the array has to be coherently coupled. In this contribution a hierarchically coupling scheme by injection-locking with one master laser is investigated. A great advantage is that the coupling strength for all emitters is nearly the same, so scaling to large arrays is easier compared to coupling schemes using direct interaction of the emitters.